21401228 has 12 divisors (see below), whose sum is σ = 37521960. Its totient is φ = 10680672.

The previous prime is 21401203. The next prime is 21401251. The reversal of 21401228 is 82210412.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2426 + ... + 6977.

It is an arithmetic number, because the mean of its divisors is an integer number (3126830).

Almost surely, 2^21401228 is an apocalyptic number.

It is an amenable number.

21401228 is a deficient number, since it is larger than the sum of its proper divisors (16120732).

21401228 is a wasteful number, since it uses less digits than its factorization.

21401228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9976 (or 9974 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21401228 is about 4626.1461282584. The cubic root of 21401228 is about 277.6384202430.

The spelling of 21401228 in words is "twenty-one million, four hundred one thousand, two hundred twenty-eight".